DARLINGTON, S.C. (AP) William Byron knows major chances at success don't come around often in a career. He plans to be as ready as he can when they come his way.

The 19-year-old Xfinity Series rookie Wednesday turned his first laps at Darlington Raceway, one of the most unique tracks on the NASCAR circuit. It's all part of his learning curve, a process that took a big step forward when he signed with powerhouse Hendrick Motorsports to race this season.

Byron won seven races - nearly doubling Kyle Busch's record for rookies of four victories in 2000 - in his only full season on the Camping World Truck Series in 2016. The next jump for him is the chance to join those rising young guns on the Monster Energy NASCAR Cup series seeking to replace retired, or soon-to-be retired, drivers like Jeff Gordon, Tony Stewart, Carl Edwards and Dale Earnhardt Jr.

"It's something that I strive for," Byron said between test sessions Wednesday. "It's something I want to be reality. But I don't know when timetable is. I want to focus on this next year, the next race, the next test."

Byron's focus Wednesday was on the laps at the track "Too Tough To Tame." He and the rest of the Xfinity Series will lineup on Sept. 2 as part of Darlington's Labor Day weekend . The Southern 500 in the premiere series will take place the following night.

It's a time of transition in the sport with iconic figures stepping away and opening the car window for young, talented drivers to jump in. Byron drives for the JR Motorsports team owned in part by Earnhardt Jr. and Hendrick Motorsports owner Rick Hendrick.

But Byron said if he spent too much time dreaming about the road ahead, he'd fall short on progressing and becoming a potential worthy replacement when the call to NASCAR's biggest series comes.

"If you're looking past that now, it's really too much for you to handle," he said.

Byron was not the only young racer making his first laps on Darlington's quirky, 1.366-mile oval. Tyler Reddick, 21, took his first few spins and got a Darlington stripe, hitting the wall hard in turn four - and giving his crash crew some work to do on their lunch break.

"They're not too happy with me right now," Reddick said ruefully.

Like Byron, Reddick had success as a truck driver with three series wins over the past two years. He was the youngest NASCAR truck winner at Daytona with his victory as a 19-year-old in 2015. Also like Byron, Reddick was signed to the Xfinity Series for this fall, driving part time for Chip Ganassi Racing.

Reddick has struggled in his four races, his best showing a 14th at Phoenix in March. He has not let the slow start rattle him or his belief that bigger things are ahead.

"There's always opportunities, even for next year," Reddick said. "Nine times out of 10, you're not going to see (the chances) coming, so you've got to be ready."

Byron is trying to prepare himself as best he can. It was humbling last August at Bristol, Tennessee, when car owner Hendrick gushed about Byron's potential for a big-time NASCAR future after he signed. What's happened this season is a complete adjustment from his truck racing time.

There are new teammates, crew members and leaders to blend with and different tracks like Darlington to learn intimately.

"It's a process," Byron said.

One that's had several bumps this season. While Byron has had five top-10 finishes and won the pole at Phoenix, he's finished 30th and 36th his past two events.

"So far, it's been a good challenge and one that I've enjoyed," Byron said. "I'm trying to take it all in and go to the different race tracks and adapt."